According to Richard Conn Henry’s calendar, eight months would each have 30 days. Every third month would have 31 days. Every so often, to account for the leftover time, a whole extra week would be added.

The upshot: Years would proceed with clockwork regularity, with no annual re-jiggering of schedules required. Each day would occupy the same position as it had the previous year and would in the next. Were this 364-day calendar, known officially as the Hanke-Henry Permanent Calendar, adopted on the first day of 2012, both Christmas and New Year’s Day would forever fall on Sunday.